Dumping vehicles, for example dump trucks and dump trailers, are frequently used as a convenient way to transport material and deposit the transported material at a destination. Dump trucks generally include a single frame attached to an engine that moves the vehicle and a dump bed that carries and deposits a payload of material. A dump trailer generally couples to a tractor with an engine, which moves the trailer from one destination to another over, for example, a roadway. Frequently, the front portion of a dump trailer is supported by the tractor and the rear portion is supported by the trailer's frame and wheels.
A dump trailer generally includes a payload-carrying dump bed that tilts to empty the dump bed and deposit the payload at the destination. One type of dump trailer is an end dump trailer that, when tilted, dumps its contents out of the back end of the dump trailer as the forward end of the payload body is rotated upward. Side dump trailers unload the contents of their payload carrying bodies off to one side of the trailer.
A dump trailer typically includes a coupler, which couples with a complimentary coupler located on the tractor. One type of coupling includes a downwardly extending pin attached to the front of the trailer that mates with a complimentary receptacle on the tractor. Fifth-wheel couplings are one example. Typically, the receptacle on the tractor is at least partially surrounded by a coupling plate with a front end that is allowed to freely tilt up and down about a horizontal axis, for example axis 56 in FIG. 1. Some tractor couplers include a mechanism that can be locked with a pin to inhibit the tractor coupler from tilting.
An example schematic of a tractor 50 is depicted in FIG. 1. Tractor 50 includes a coupler 52 that pivots about pin 54. Pin 54 defines a horizontal axis 56 about which coupler 52 rotates (tilts). To connect the trailer to the tractor, the driver typically backs the tractor under the trailer and the downwardly extending pin slides along the tractor coupling plate until it mates with the pin receptacle. The tractor coupling plate usually includes a latching mechanism that holds the trailer pin in the tractor's pin receptacle. The coupling between the tractor and the trailer allow the tractor and trailer to pivot with respect to one another about a vertical axis and allows the tractor-trailer combination to maneuver and turn while being driven over, for example, a roadway. Typically the coupler on the tractor can pivot along a horizontal axis to accommodate the flexing of the tractor-trailer rig as it travels over high and low points in the roadways, such as crests and valleys in the pavement.
Dumping vehicles are used to transport material from one location to another. The forward end of the dump trailer is raised to deposit the payload material at the destination, and frequently into a receiving container. In typical paving operations, raw asphalt material is transported in a dumping vehicle, such as a dump truck or dump trailer, and is then dumped or pushed into a hopper adjacent the rear of the truck. The hopper then feeds the material to the paving equipment which lays the material as asphalt paving. When involved with this type of operation, it is preferred that the paving material be dumped directly from the dumping vehicle into the hopper without spilling material onto the surrounding area.
To accommodate this operation, typically an asphalt hopper is positioned very close to the rear of the dump trailer with the front edge of the hopper underneath the trailer's sill. Spacer wheels can be placed on the hopper which abuts the trailer's rear wheels to provide the correct spacing. Prior trailers have allowed the trailer sill to overlap the hopper by having the rear wheels of the trailer offset inward approximately 12 inches or more from the rear edge of the trailer.